The invention relates to a fluid friction clutch, in particular for use in a motor vehicle and in particular having a rotatably mounted shaft, a drive body mounted in a rotationally fixed manner on the shaft, an output body mounted rotatably on the shaft and at least partially surrounding the drive body, and a clutch region arranged between the drive body and output body which accommodates a viscous fluid and can be used to couple drive body and output body in order to transmit a torque.
Conventional fluid friction clutches of this type have a reservoir for a hydraulic fluid and a clutch region. In the clutch region, the forces are transmitted with the aid of hydraulic fluid which, when the clutch is actuated, is conveyed into the clutch region from the reservoir as a result of centrifugal forces. To be deactivated, the fluid is pumped back from the clutch region into the reservoir. This is effected, for example, by means of a ram pump which generates a ram pressure between the drive body and output body.